Temperature-actuated valve assemblies, which open or close at a predetermined temperature, are known in a wide variety of industries. In the avionics field, temperature-actuated valve assemblies are commonly employed as over-temperature shutoff valves in aircraft bleed air systems. Such over-temperature shutoff valves are configured to close, and thus protect temperature-sensitive downstream components, when the fluid conducted by the valve assembly becomes too hot. Over-temperature shutoff valves of this type may employ thermal fuse plugs made of eutectic alloys that abruptly melt at a predetermined actuation temperature. The eutectic fuse plug may maintain a spring-loaded flapper (or other such valve element) in an open position. When the bleed air heats the eutectic fuse plug to its melting point, the fuse plug melts, and the flapper is permitted to swing shut.
Though over-temperature shutoff valves of the type described above are effective for decreasing airflow when bleed air surpasses a particular temperature threshold, the eutectic plugs employed by such shutoff valves require replacement after valve actuation (i.e., valve tripping). In addition, such control valves cannot be tested to ensure proper operation without heating and melting the eutectic plug. Although over-temperature shutoff valves have been developed that employ non-perishable temperature-sensitive elements (e.g., shape memory alloy actuators), such over-temperature shutoff valves may still require manual intervention to be reset.
Considering the foregoing, it is desirable to provide a temperature-actuated valve assembly (e.g., an over-temperature shutoff valve) configured to actuate (e.g., close) when the fluid flowing through the assembly exceeds a first predetermined temperature. It would also be desirable if such a valve assembly were configured to automatically reset (e.g., re-open) when the fluid cools below the first predetermined temperature or, perhaps, a second predetermined temperature that is lower (or higher) than the first predetermined temperature. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.